Bone plates and other implants can be engaged to adjacent bony portions of a bone or of a bony segment to stabilize the bone portions. Fasteners can be used to engage the implant to the bony portions. To prevent the fasteners from backing out of the underlying bone relative to the implant, various retaining devices have been developed for engagement to the implant adjacent to or around the bone fasteners. Some retaining devices are in the form of set screws, washers, arms or flaps that interfere with the bone screw if it moves into contact with the retaining device. These retaining devices block the fasteners to prevent them from backing out of the implant.